Capacitor manufacturing evaporation apparatus



Oct. 21, 1952 H. E. HAYNES 2,614,524

cAPAcI'roR MANUFACTURING EvAPoRATIoN APPARATUS XNVFNTOR HARUILU EL,AL/NES BY t ATTO R N EY H. E. HAYNES CAPACITOR MANUFACTURINGEVAPORATION APPARATUS Oct. 21, 1952 original File. Aug. 22, 1946 2vSHEETS- SHEET 2 INVENTOR S E vNl A H E. D o R A H BY I 7" ATTORNEY rbyreferring to the which: i o f Fig. 1 is a cross-section ci the capacitorof this Patented Oct. 21, 1952 lUNITED STATE cArAorron s PATENT OFFICEMANUFACTURING EVAPORA- TION APPARATUS y Harold E. Haynes, Audubon, N.J., assigner to Radio Corporation of America, a corporation of DelawareClaims.

The present inventionrelates toan improved electrical capacitor and amethod of constructing the same. y

This application isadivisional application of my copending applicationSerial No. 692,355, iiled August 22, 1946. now abandoned, whichapplication was directed to the condenser structure, whereas thisdivisional application is directed to the machine and process.

An object of the invention is to provide a capacitor `having a highvalue of capacitance relative to the space occupied, having stability ofcapacitance value and being suitable for use in alternating currentcircuits.

The capacitor of this invention is made up of alternate layers ofevaporated dielectric and evaporated metallic conducting llayers ofiilms. The capacitor is built upon an insulating sheet or a thin sheetof metal by evaporating first a dielectric layer, then applyingalternately extending metallic layers, then another dielectric layer,etc. i

In theconventional alternate-layer type of'capacitor construction,` thefactors which m-ake for Ahigh capacitance in small space are (1)thinness of dielectric, (2) high dielectric constant, and (3) thinnessof conducting platesso asfnct to occupy more space thannecessary. Thisinvention provides a means of realizing large improvements in factors 1and 3. i

This invention involves a process 'wherein 4a capacitorfis made byevaporating alternate layers of conducting and non-conducting materials,

with suitable electrical connections, the conducting lms being onlythick enough to provide satisfactorily low resistance and the dielectricfilms .only thick `enough to withstand the required working or peakvoltage.

The invention will be more clearly understood ac-companying drawing, in

invention;

Fig. 2 is a sectional view of Fig. 1, the section beingtaken on line2-2;

, Fig. 3 is a sectional view of Fig. 1, the section being taken on line3-3; f l

Fig. 4 is a -plan vlewof the capacitor building machine and mask' f Fig.5 is a sectional elevationoi the capacitor rbuilding machine of Fig. 4;,and` n',

Fig. 6 isa detailed plan view of Fig. 5.

Referring now to Figs. l, 2 and 3 of the drawings, an insulating base ormatrix I has secured thereto 'metallic terminal members 2 and3. Theterminal members Zand 3 are secured in a semicircular recessed portionon base I by means yof pins 4 and 5.` `The capacitor of thisinvention isbuilt upon rriatrix` by having a iirst layer of coatings comprising ametal portion I0, a dielectric portion II and a metal portion I2deposited thereon. The various metallic and dielectric portions areplaced in position on matrix condenser.

2 by meansoi a machine having suitable masks which will be described inmore detail in connection with Figs. 4, 5 and 6. The second layercomprises a metal portion |3, a dielectric portion I4 and a metalportion I5. The third layer comprises a metal portion IE, a dielectricportion and a metal portion I8. The fourth layer comprises a metalportion I3, a dielectric portion 20 and a metal electrode portion .2|.These four layers complete one cycle of operation in building thecapacitor section or stack. The iifth layer is a repetition of the rstmentioned layer and comprises metal portion |0, dielectric portion I I,and metal portion I2. It is to be noted that the metal portions I2, I3,I5, I6, I9 and 2| form metallic spacing members, the kthickness of aspacing member being substantially the same as dielectric members I4and20. The rst layer comprises the metallicportion I0 which forms thepositive electrode of the condenser. The insulation portion II forms adielectric spacer or barrier between the positive electrode I0 and ametal spacing member I2. The second layer comprises a metallic spacingmember I3, the condenser dielectric |4 and a metallic spacing member l5.The third layer includes a metallic spacin-g member IG, a dielectricspacer or barrier portion Il, and a metallic portion I8. The metallicportion I8 serves as the negative electrode of the The fourth layercomprises metallic portion I9, -dielectric portion 20, and metallicspacing portion 2|. The capacitor stack is built up of -any numb-er oflayers by repeating the cycle mentioned above which includes metallicand dielectric portions l0 to 2|, inclusive. The insulation base ormatrix may be of metal with an insulation coating (not shown), and meansprovided suchas insulating bushings (not shown) to tinsulate theterminals.

The manner in which these layers are built up will be more completelyunderstood by referring to Figs. 4, 5 and 6, showing the capacitorbuilding machine and maskk above which the matrix I is secured by anysuitable means Within a vacuum chamber 30, which is preferably in theform of a bell jar.l There is located within the bell jar v3U a circulardisc 3| which is driven Vby a motor 32. Themotor is preferably geareddown to kallow conveniently slow operation (by any suitable means, notshown). The disc 3| has a plurality of apertures, indicated by theletters A to L, inclusive. The apertures are properly shaped Aand solocated on the discas to form a mask to properly evaporate thedielectric and conductive material in a proper sequence` to lform thecondenser layers `rdescribed above in connection with Figs. l', 2 and 3.The disc 3| has the twelve apertures A to L, inclusive, spacedapproximately y30" apart, which will allow deposition of the rtwoevaporated materials, in proper sequence. and shape upon the matrix I.For example, aperture A is to permit depositing metal to form 'theconductive layer I; aperture B is to permit depositing a narrow strip ofdielectric material forming the barrier I I; and aperture C permits adeposit of conductive material to form the spacer I2. These threeapertures complete the forming of the rst layer. Aperture D permits adeposit of metal to form spacer I3; aperture E permits a deposit ofdielectric material to form the condenser dielectric I4; and aperture Fpermits a deposit of conductive material to form the spacer I5. Theapertures D, E and F thus complete the second layer. The third layer isformed by having aperture G permit the deposit of conductive material toform the spacer IS; aperture H forms the dielectric barrier II; andaperture I forms the electrode I8 by depositing conductive material onthe previously formed layers I and 2. The fourth layer is accomplishedby having aperture J permit a deposit of conductive material to form thespacer I9; aperture K permits the deposit of dielectric material to formthe condenser dielectric by depositing conductive material over thethird layer; and the final operation is accomplished by having apertureL permit the deposit of conductive material to form the spacer 2|. Whenthis sequence or cycle of operation has been completed, the disc is thenback at its starting position and another cycle of operation isaccomplished by placing layers 5, 5, I and 8 upon the previously formedlayers I, 2, 3 and 4. Any number of layers may be built up to obtain thedesired condenser capacity. However, if desired, a complete condensersection may comprise only the first four mentioned layers. The completedsections may be stacked up and connected either in series or parallel.

Apertures A to L, inclusive, mentioned above, serve to indicate how therotation of the mask may be continued on throughout its rotatable lengthby repeating the cycle of capacitor building operation. Located beneaththe mask 3| are two vessels and 3G. The vessel 35 contains theconductive material to be evaporated upon matrix I and the vessel 36contains the dielectric material to be evaporated upon matrix I.

Opposite the apertures A, C, D, F, G, I, J and L in disc 3|, and locatedon its periphery, are V-shaped detents 3? whose depth is made such as tocause a cam follower 38 (which is pivoted at 319 by means of a pin 38)to actuate a second mask 40. Opposite the apertures B, E, H and K areV-shaped detents 31A which have a greater depth than detents 3T andtherefore, move mask a greater distance. 'I'he mask 4D is pivoted to thelower part of 38 and has an aperture 40A which is locatedI below theapertures in disc 3| and just above thev vessels 35 and 36, so that byaction of cam follower 38 and its associated parts, moving the mask 40,there will be produced a stream of the desired evaporated materialswhich are located in vessels 35 and 35. Suitable heating means forvessels 35 and 36 are located at 42.

The lever arm or cam follower 38 is held against the periphery of discV3| by means of a spring 4I which applies spring tension at the fullradius of the disc, except when evaporation is desired. In the positionof the full radius, the mask 40 (operated through lever 38 and pivot 39)covers both the vessels 35 and 38 containing the conducting material anddielectric material, respectively. The disc 3| is rotated by motor 32 toa position such that one of the apertures is directly below the matrix Iupon which the capacitor is to be built. In this position the spring 4|urges the cam follower 38 to drop into the corresponding detent, causingthe second mask 40 to uncover the proper vessel and thus evaporate thedesired material.

In the position shown in Fig. 4 (the detent being in position A), aconductive layer will be deposited upon the matrix I because in thisposition aperture 40A in the second mask uncovers vessel 35. In positionB, the detent 31A is of greater depth and therefore causes member 38 tomove a greater distance, which will then uncover vessel 36 to depositdielectric material on matrix I. The entire sequence of operationsmentioned above will be accomplished by having the lever 38 drop in thedetent located adjacent to the aperture, the entire operation beingautomatic by merely causing the motor to operate for the proper time andat the right interval. The position of the vessels will not need to bechanged, since they are located far enough from the apertured disc 3| soas to cause the material to be deposited in nearly the same position,irrespective of which vessel is uncovered by the second mask 40.

In the operation of this device, the appropriate materials for thedifferent phases of the cycle of operation are heated and evaporatedcontinuously from the two boats or vessels 35 and 36 which are coveredand uncovered by mask 40, the mask 40 being operated in the properrelation to the position of the first movable mask 3|. When part A ofmask 3| is located below the inch-square capacitor being built (or anyother desired size). conducting material from boat 35 is evaporated onmatrix I to a thickness equal to that of the dielectric. This formselectrode I0 of the capacitor. When part B is over the working area, thedielectric barrier is formed on matrix I by cam follower 38 moving themask 40 to uncover boat 36. At part C, a spacer is formed on matrix I byevaporation of metal from boat 35. These three operations complete thefirst layer. At part D more conducting material from boat 35 isevaporated over the first layer to the desired thickness to form asecond spacer. Part E forms the dielectric over the first layer. Part Fforms a third spacer. Part G forms a spacer over the second layer. PartH forms a dielectric barrier over the second layer. Part I forms thesecond electrode I8 over the second layer. Part J forms a spacer on thethird layer. Part K is for forming the'dielectric material over `thethird layer. Part L is a metal spacer over the third layer. These lastthree operations complete the fourth layer. The next unit or additionallayers ofthe capacitor is then built up beginning again at A.

I have found that convenient conducting materials should be copper orlsilver, since they have low resistance and lend themselves well toevaporation. The dielectric may be any (or a combination) of severalmaterials of which some preferred ones are magnesium fluoride, quartz.and aluminum oxide.

A calculation of the properties of a capacitor made by this method is asfollows: Assume a plate area of one square inch, conducting layerthickness of 1/100,000 inch, dielectric thickness of l/50,000 inch. Ifthe conductor is a square inch of copper 10-5 inch thick, it will have aresistance from one edge to the opposite edge of 0.07 ohm, which shouldbe sufficiently low. If the dielectric constantv of the insulationmaterial is, say 5, and the dielectric strength is 500 kv./cm.. thecapacity per layer of dielectric will be 0.056 mf. and the breakdownvoltage may be estimated as 25.4. If the capacitor were built upaccording to this invention to a thickness of say 0.1 inch, it wouldhave a rating of 18,700 mf. at about volts. For higher voltage uses, acapacitor could be made in the same space to have. say, 187 mf. at 100volts, or 1.87 mf. at 1000 volts. The 187 mf. condenser would have atotal of 666 evaporated layers (which indicates the necessity of amachine as disclosed by Figs. 4, 5 and 6 to complete the processes ofthe stack construction). Since the exact thickness of layers would notbe critical, many of the problems encountered in evaporating lms ofspecial optical properties would not arise.

The mask for the boats and the mask for forming the layers move insynchronism and in proper phase with each other beneath the capacitorstack being built up.

As is mentioned above in connection with Figs. 1, 2 and 3, the capacitorstack thus formed is one of a solid stack comprising alternate layers ofdielectric and metal material and when used for high voltages it isdesirable that the stack be imbedded in a plastic case such as,forexample, polystyrene, indicated at 70.

What is claimed is:

1. An electrical capacitor building machine comprising a means to retaina base member of insulation material within an evacuated vessel, amovable disc having apertures therein located beneath one of thesurfaces of said base of insulation material, means to move said discwith respect to the surface of said base of insulation material, two xedvessels, one for holding a metal and the other for holding a dielectricmaterial, said fixed vessels each being positioned beneath certainapertures in said movable disc, a movable mask above said fixed vessels,cam means for simultaneously moving said disc and said mask with respectto said fixed vessels to progressively coat thin layers of metal anddielectric material on said base to form a capacitor.

2. In apparatus for vacuum coating a workpiece by evaporating means,means to selectively apply coatings of at least two differentcharacteristics including a selectively positionable masking elementhaving a plurality of apertures therein, a positionable gating elementhaving an aperture therein, said elements being interposed between saidworkpiece and said evaporating means with at least one aperture of saidmasking element and the aperture of said gating element aligned withsaid workpiece and said evaporating means, and means responsive to thepositioning of said masking element selectively to position said gatingelement to select the desired one of said evaporating means to apply thecoating corresponding to the aperture of said masking element andcorresponding to the selected evaporating means.

3. In apparatus for vacuum coating a matrix by evaporating means toselectively apply coatings of at least two different characteristics. aselectively rotatable disc member having a plurality of aperturestherein, and a plurality of notches around the periphery thereofcorresponding to said apertures, a slideable plate member having anaperture therein, said members being mounted between said matrix andsaid evaporating means with at least one aperture of said disc memberand the aperture of said plate member aligned in a plane defined by saidmatrix and said evaporating means, a pivotally mounted link connected atone end to said plate member and having the other end engaging thenotches of said disc member, said notches varying in depthscorresponding to the number of said coatings to position said platemember in response to the positioning of said disc member to select thedesired one of said evaporating means to apply a coating to said matrixcorresponding to the apertures of said members.

4. In apparatus for vacuum coating a matrix by evaporating means toselectively apply coatings of at least two different characteristics,two evaporating boats, a plate positioned over said evaporating boats,said plate having an aperture therein to permit vapor to rise from oneof said boats, a rotatable disc having a plurality of apertures thereinand a plurality of notches about the periphery thereof, said notchesbeing of different depths corresponding to the number of said coatings,said disc being mounted beyond said plate with at least one aperture ofsaid disc aligned in the plane dened by said matrix and said evaporatingmeans, said matrix being mounted beyond said disc with the aperture ofsaid plate also aligned in said plane, a lever pivotally arrangedbetween said disc and said plate, one end of said lever engaging thenotches of said disc and the other engaging said plate to position saidplate in accordance With the position of said disc to select a desiredone of said evaporating means to apply the coating corresponding to theapertures of said plate and said disc.

5. In apparatus for vacuum coating a matrix by evaporating means toselectively apply coatings of at least two different characteristics,two evaporating boats, a plate positioned over said evaporating boats,said plate having an aperture therein to permit vapor to rise from oneof said boats, a masking member having a plurality of apertures thereinand a plurality of depressions arranged therein each corresponding toone of said apertures, said depressions being of different depths in agiven direction corresponding to the number of coatings, said maskingmember being mounted beyond said plate with at least one aperture ofsaid masking member and the aperture of said plate aligned in the planedefined by said matrix and said evaporating boats and arranged inmoveable relationship thereto, a lever pivotally arranged between saidmasking member and said plate, one end portion of said lever engagingthe said depressions as a detent and the other end engaging said plateto position the same in accordance with the position of said maskingmember to select a desired one of said evaporating boats to apply thecoating corresponding to the apertures of said plate and said masinkgmember.

HAROLD E. HAYNES.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,926,842 Dubilier Sept. 12, 19332,160,981 OBrien June 6, 1939 2,341,827 Sukumlyn Feb. l5, 1944 2,391,595Richards et al Dec. 25, 1945 2,398,176 Deyrup Apr. 9, 1946 2,410,720Dimmick Nov. 5, 1946 2,432,950 Turner et al Dec. 16, 1947 2,456,708Kellog Dec. 21, 1948 2,482,329 Dimmick Sept. 20, 1949

